Oop flow

ABSTRACT

METHOD FOR THE REAL-TIME CONTROL OF THE RESISTIVITY OF AN EPITAXIALLY GROWING CRYSTAL BY A SPECIALLY PROGRAMMED PROCESS CONTROL COMPUTER. THE DILUENT HYDROGEN, THE ARSENIC DOPENT AND THE DILUTED ARSENIC DOPANT GAS FLOW RATES OF A SILICON TETRACHLORIDE-ARSINE REACTION SYSTEM ARE CONTROLLED SIMULTANEOUSLY TOWARD VALUES DETERMINED IN ACCORDANCE WITH RESPECTIVE MONOTONIC FUNCTIONS OF A PARAMETER S SATISFYING THE RELATIONSHIPS BETWEEN THE AFORESAID THREE GAS FLOW RATES AND THE RESISTIVITY VALUE OF THE EPITAXIAL LAYER. THE ACTUAL GAS FLOW RATES ARE MONOITORED AT PREDETERMINED INTERVALS DURING EPITAXIAL GROWTH AND   A COMPUTED RESISTIVITY FUNCTION R THEREOF IS COMPARED TO THE SAME COMPUTED FUNCTION BASED UPON DESIRED GAS FLOW RATES. ANY DEVIATION IN EXCESS OF A PREESTABLISHED AMOUNT CAUSES THE COMPUTER TO INCREMENT THE VALUE OF THE PARAMETER S UNTIL A NEW REALIZABLE COMBINATION OF GAS FLOW RATE VALUES IS FOUND WHICH WOULD RESTORE THE DESIRED RESISTIVITY VALUE OOF THE GROWING EPITAXIAL LAYER.

DEFENSIVE PUBLICATION UNITED STATES PATENT AND TRADEMARK OFFICE Published at the request of the applicant or owner in accordance with the Notice of Dec. 16, 1969, 869 O.G. 687. The abstracts of Defensive Publication applications are identified by distinctly numbered series and are arranged chronologically. The heading of each abstract indicates the number of pages of specification, including claims and sheets of drawings contained in the application as originally filed The files of these applications are available to the public for inspection and reproduction may be purchased for 30 cents a sheet.

Defensive Publication applicationshave not been examined as to the merits of alleged invention. The Patent and Trademark Ofiice makes no assertion as to the novelty of the disclosed subject matter.

PUBLISHED MAY 6, 1975 T934006 Xl n 0 SET Pomt COMPUTER CONTROL FOR REAL TIME DETERMI- X2 ,5, SET pom NATION 0F RESISTIVITY 0F EPITAXIALLY X5-DD0P SET GROWING CRYSTALS I R -x2*x3/(x2+xn Ronald E. Chappelow, Wappingers Falls, Leo E. Elijah, F

Beacon, Virgil L. Elliott, Newburgh, Edward G. l )(4- HZDACTUAL 2o Grochowski, Wappingers Falls, Harry D. Harrison, x5- 00? ACTUAL Beacon, Homer A. Tice, Hyde Park, and Ralph S. l ;i 2 2 & i

York, Wappingers Falls, N.Y., assignors to International Business Machines Corporation, Armonk, NY. Continuation of application Ser. No. 97,235, Dec. 11, i 1 BEV-ABS(lRRAl/R) 1970. This application Nov. 19, 1973, Ser. No. 416,893

Int. Cl. G06f 15/46 1 23 22 U.S. Cl. 235-151.1 -O DH 0 1 4 Sheets Drawing. 29 Pages Specification ix! Method for the real-time control of the resistivity of an epitaxially growing crystal by a specially programmed process control computer. The diluent hydrogen, the mhmpmho -I arsenic dopant and the diluted arsenic dopant gas flow rates of a silicon tetrachloride-amine reaction system are controlled simultaneously toward values determined in accordance with respective monotonic functions of a 28 parameter S satisfying the relationships between the afore- 0 0 said three gas flow rates and the resistivity value of the 32 -"pze epitaxial layer. The actual gas flow rates are monitored Writ i x4 at predetermined intervals during epitaxial growth and a computed resistivity function R thereof is compared to i..

the same computed function based upon desired gas flow nzv ABS (tie-x5) /x2) rates. Any deviation in excess of a preestablished amount causes the computer to increment the value of the parameter S until a new realizable combination of gas flow rate values is found which would restore the desired resistivity value of the growing epitaxial layer.

May 3, 1975 Original Filed Dec. 11, 1970 XZA R. E. CHAPPELOW ETAL COMPUTER CONTROL FOR REAL TIME DETERMINATION OF RESISTIVITY OF EPITAXIALLY GROWING CRYSTALS XZA 4 Sheets-Sheet 1 INVENTORS RONALD E. CHAPPELOW LEO M. ELIJAH VIRGIL L. ELLIOTT EDWARD G. GROCHOWSKI HARRY D. HARRISON HOMER A. TICE RALPH S. YORK A TT NEY p far -=1 ta WM? R. E. CHAPPELOW ETAL T 349 COMPUTER CONTROL FDR REAL TIME DETERMINATION OF RESISI'IVTI'! OF EPITAXIALLY GROWING CRYSTALS Original Filed Dec. 11., 1970 4 Sheets-Sheet 2 /1 x1= H20 SET POINT 9 x2 DOP SET POINT x5 n DOP SET POINT R x2*xs/ x2+x1) 20 x4 H20 ACTUAL x5 DOP ACTUAL X6 =0 DOP ACTUAL RA xsae xe /(xs+xs) 21 DEV ABS ((R-RA )/R) i 26 FIX1= F|X2=FIX3=0 m 27 FIG. 5A 5A 05v ABs((x1-x4)/x1) FIG. 58

FIG. 5C ,30

IVER! May g! R. E. CHAPPELQW Ema. T934306 COMPUTER CONTROL FOR REAL TIME DETERMINATION OF RESISTIVITY OF EPITAXIALLY GROWING CRYSTALS Original Filed Dec. ll, 1970 4 Sheets-Sheet 5 &

RINCR .01

FROM BLOCKS 79 AND 85 S =S+SIGN* RINCR FIG. 5B

May 6, 1915 COMPUTER CONTROL R. E. CHAPPELOW EI'AL A FOR REAL TIME DETERMINATION OF RESISTIVITY OF EPITAXIALLY GROWING CRYSTALS Original Filed Dec. 11, 1970 4 Sheets-Sheet 4 DEV ABS(DEV) RINCR RINCR l2 SIGN*1*SIGN IRAY(LLLL)= IRAY(LLLL)= 53 24*s 14o -14o *5 76 A ae\ IRAY(LLLLL)= 12 *s+1e 7 IRAY(LLLLM)-42*S+54 ALARM mmcAToR RESET ALARM INDICATOR T0 ZERO RETURN TO BLOCK 19 

